SteemIt notifies me when I reply to my own post:

![Screenshot 2017-06-11 21.23.05.png](https://steemitimages.com/DQmRq3DUuhvPiqCQ1BaY5iLPvya41c5fT8oDN8mBLXBXS3w/Screenshot%202017-06-11%2021.23.05.png)

As I am software developer myself, so I thought I'd go to the SteemIt site on Github, make a fix for this and submit a pull request. However when I searched for the word 'mentioned' I could not find it. Which implies that the server push which triggered this notification is not open source, or at least on a separate project.  

Does anyone know if all of SteemIt is open source or are there some parts, such as the notifications engine, which are closed?    I'm asking because I am quite interested in look at notifications with a view to developing some additional features in this area....